Optimization of surfactin production by Bacillus subtilis ATCC 6633 in a miniaturized bioreactor

In recent years, biosurfactants due to wide applications in chemical, petroleum, food and pharmaceutical industries, have been widely considered by researchers. Biosurfactants are produced by a series of microorganisms, so it is important to screen culture medium and operating conditions in miniaturized bioreactors prior to scaling up to large bioreactors.In this study, using a kind of miniaturized bioreactor called ventilation flask, optimal production conditions, including filling volume and shaking frequency to produce a surfactin-type biosurfactant by Bacillus subtilis ATCC 6633, were examined. Moreover, the effect of oxygen transfer rate [OTR] on the surfactin production was investigated according to Amoabediny and Buchs model. The results indicated that the maximum biomass and biosurfactant yield which obtained under optimal conditions [filling volume of 15 mL and shaking frequency of 300 rpm] were evaluated 0.3 g/L/h and 0.0485 g/L/h, respectively. Also, at the same conditions, the amount of surface tension decreased from 60.5 mN/m to 31.7 mN/m and the maximum oxygen transfer rate [OTR[max]] obtained as 0.01 mol/L/h

Effect of aeration rate on biosurfactin production in a miniaturized bioreactor

Recently, the production of biosurfactants in bioreactors and their use in various pharmaceutical, chemical and food industries have been developed. Optimum production is directly related to the physicochemical condition of culture medium [such as pH and temperature] and engineering parameters of bioreactors [such as aeration rate, volume of operation and the amount of energy input]. Understanding the gas transfer in shaken bioreactors equipped with a sterile closure is advantageous to avoid oxygen limitation or carbon dioxide inhibition of a microbial culture. In this study, the effect of aeration rates [due to using different design closures] on the amount of biosurfactin production by Bacillus subtilis ATCC 6633 in a ventilation flask as a miniaturized bioreactor was investigated. The highest biosurfactin concentration [0.0485 g/L/h] was obtained in the optimum conditions in which the amount of filling volume and shaking frequency were 15 ml and 300 rpm, respectively. The specific aeration rate [q[in]] and maximum oxygen transfer rate [OTR[max]], were calculated 1.88 vvm and 0.01 mol/L/h, respectively. The results showed the significant biosurfactin productivity increase under non-oxygen limiting condition